The present invention relates to fitness equipment and, more particularly, to interlock apparatus for actuating safety locks on fitness equipment.
Safety features such as brakes or locks on load-bearing components of fitness and exercise equipment are often important to reduce the chance of personnel injury or equipment damage. By example, U.S. application Ser. Nos. 09/201,434 and 09/385,241 disclose self-spotting apparatus for free-weights having pressure-sensitive grip actuators on the barbells and dumbbells that lock support cables if either grip actuator is released. U.S. Pat. No. 4,998,721 discloses a weightlifter""s exercising apparatus having a brake means discretionally controlled by the athlete at the handgrip positions.
While such grip actuators provide desired convenience or safety functions in many cases, conditions arise in which added capabilities to sense abnormal conditions, either in the apparatus or use of the apparatus is needed. For example, connection or re-connection of sensors, which may be required when changing from barbells to dumbbells in fitness equipment, can result in reduced effectiveness of the safety features, convenience features or interlocks. Environmental changes can result in circuit drift, especially if the sensors are analog devices.
Therefore, an object of the present invention is to provide interlock apparatus for fitness equipment which actuates safety features such as safety locks or brakes when an operator is not adequately gripping load-bearing components of the equipment.
Another object of the present invention is to provide interlock apparatus for fitness equipment which senses abnormal operation of the equipment and maintains the equipment in a safe mode.
Another object of the present invention is to provide interlock apparatus for fitness equipment which senses disconnection of grip sensors of the apparatus and modifies the signal verification logic to maintain safe operation upon re-connection of the grip sensors.
Another object of the present invention is to provide interlock apparatus for fitness equipment which provides reliable safety interlock operation when disconnecting and re-connecting different load-bearing components.
Still another object of the present invention is to provide sensors which utilize capacitance or inductance of the body to provide g rip signals, thereby eliminating mechanical switches and providing additional data for use by a logic processor.
The interlock apparatus of the present invention utilizes one or more engagement or grip sensors attached to user-engageable load-bearing components of fitness equipment such as self-spotting free-weight bars, dumbbell bars, fitness equipment lift bars, curl bars, foot pedals, etc. The interlock apparatus provides grip signal validity checks to ensure that safety features such as brakes or locks are activated when required and makes the apparatus less prone to inadvertent activation by invalid signals. The interlock apparatus goes beyond simple xe2x80x9con-offxe2x80x9d pressure witches such as micro switches by providing xe2x80x9csmartxe2x80x9d features that ensure activation signals are valid operator-actuated signals.
In the preferred embodiments, the interlock apparatus comprises a grip sensor such as a capacitance sensor that senses the capacitance of the body when the operator makes touch contact when gripping the load-bearing component in the proper manner. The grip sensor is connected to a logic processor having a memory, such as a microprocessor, through a signal conditioner. The signal conditioner provides a digital output for processing by the logic processor, noise filtering and de-bouncing of the signal from the grip sensor.
In the preferred embodiments, the signal conditioner also provides a grip status signal to the logic processor for determining the validity of the grip signal. In the preferred embodiments, the grip status signal is a digital pulse signal proportional to the amplitude of the grip signal from the grip sensor. In other embodiments, the grip status signal comprises a signal corresponding to a cardiovascular or heart pulse signal. In still other embodiments, the grip status signal is a continuity signal from a separate grip sensor continuity sensor or circuit. The grip status signal may be multiplexed or otherwise combined with the grip sensor signal output of the signal conditioner connected to the microprocessor. In other embodiments a separate grip sensor status monitor provides the sensor status signal.
The microprocessor utilizes a first predetermined validity criteria to provide an interlock function based on receipt of a grip signal. In the simplest case, receipt of an xe2x80x9cactivexe2x80x9d signal from the grip sensor when the sensor status signal meets a predetermined grip status range satisfies the first validity criteria. Upon a change in the grip status signal, resulting in the sensor status signal not meeting the predetermined grip status range, the microprocessor provides a second predetermined validity criteria which is different from the first validity criteria.
The second validity criteria provides the ability of the logic processor to compensate for known or suspected conditions detected in the grip status signal. For example, the microprocessor may ignore a subsequent xe2x80x9cactivexe2x80x9d grip signal after a changed grip status signal which indicates disconnection of the sensor, even if the grip status signal returns to the predetermined range, since the subsequent xe2x80x9cactivexe2x80x9d grip signal may be due to reconnection of the grip sensor. In this case, the second validity criteria of the microprocessor evaluates the subsequent xe2x80x9cactivexe2x80x9d grip signal as invalid, even if the status signal is in an otherwise valid range.
Many other validity criteria may be employed by the logic processor to correct anticipated problems detectable by the grip status signal. For example, the logic processor may ignore any xe2x80x9cactivexe2x80x9d grip signals that, upon processing of the grip status signal by the microprocessor, indicate a changing or insufficient contact or grip on the grip sensor. Or, the logic processor may ignore otherwise xe2x80x9cactivexe2x80x9d grip signals upon loss of a cardiovascular or heart pulse signal detected by the grip sensor or separate pulse sensor. In still another embodiment, a signal duration requirement of the first validity criteria may be changed upon a change in the grip status signal.
In the preferred embodiments the logic processor also provides signal conditioning changes upon receipt of a change in the grip signal status in order to enhance the operation of the interlock apparatus. For example, upon receipt of a changed grip status signal indicating a disconnection in the grip sensor, the signal conditioner may be xe2x80x9cresetxe2x80x9d or xe2x80x9crecalibratedxe2x80x9d by the logic processor when a subsequent change in the grip status signal indicates the sensor has been re-connected. In this way, future xe2x80x9cactivexe2x80x9d grip signals will be properly evaluated as xe2x80x9cactivexe2x80x9d signals by the apparatus.
In a preferred embodiment of the invention, an analog grip sensor is utilized to provide an output proportional to a gripping action. In the preferred embodiments, a field-sensitive sensor, such as a capacitance sensor or an inductance sensor is used. Such a sensor, attached to a load-bearing component of fitness equipment such as a barbell bar, utilizes a capacitance or inductance field established between a part of the body and the sensor to provide the grip sensor signal. Such a field-sensitive sensor does not require a mechanical action of the sensor, such as that required by a mechanical switch. The output of such a sensor is proportional to closeness of the body portion to the sensor or, more preferably, the contact made with the sensor. Such an output can be used by the grip sensor status monitor to determine the validity criteria of the device.
Such a field-sensitive sensor also has the advantage of requiring only a single electrical conductor to couple the sensor to a logic processor through a signal processor or conditioner. In the preferred embodiments, a cable supporting the load-bearing component of the fitness equipment provides the electrical connection between the field-sensitive sensor and the signal processing portions remotely located on the fitness equipment.